Below:

WASHINGTON — The U.S. government, insurer of last resort, faces a potential payout of at least $919 billion under a worst-case scenario of flood and crop losses due to global warming, congressional investigators say.

That total has grown from about $209 billion in 1980, and could be even higher today because it is based on two-year-old data, according to a report. It recommends an analysis of the potential long-term implications of climate change for federal flood and crop insurance programs.

Lieberman and Maine Sen. Susan Collins, the committee's top Republican, requested the report from the Government Accountability Office, an arm of Congress.

Collins said the report shows that "global warming also threatens to burden consumers and taxpayers with billions of dollars in added costs as insured losses from floods and storms cause increases in federal spending and insurance premiums."

Because of that, the GAO recommended more research to help Congress keep a lid on "an emerging high-risk area with significant implications" for the budget.

Mark Keenum, agriculture undersecretary for farm and foreign agricultural services, said his department generally agreed with the report. But he said the main cause of catastrophic losses for the crop insurance program is drought. He added that the program's growth, rather than more severe or frequent bad weather, explains the increase in federal claims.

Conrad Lautenbacher, administrator of the National Oceanic and Atmospheric Administration, said its studies have shown a surge in population growth among coastal communities: almost 40 million more in 2000 than there were in 1970.

With more people making themselves vulnerable to winter storm surge, wind damage and hurricanes, he said, "these vulnerabilities, due to high risk coastal development, will only be amplified by climate change-related increases" in more frequent and severe bad weather.

During the quarter-century studied, private and federal insurers paid $321 billion to settle weather-related losses, mainly from hurricanes and droughts.

Weather-related losses made up 88 percent of all the property claims paid by insurers between 1980 and 2005. Other losses were caused by the Sept. 11 attacks, earthquakes and other factors, according to the GAO.